Field of the Invention
The present invention relates to an image processing apparatus capable of determining an edge type of an image, an image processing method, and a storage medium.
Description of the Related Art
For a recent printer or copy machine, an attempt is made to improve output image quality by performing various kinds of image processing for an edge portion where the shade changes rapidly in an input image. For example, in order to cancel a change in line width, which occurs resulting from a dot gain, it is known that line width correction processing to increase or reduce the line width of a character and a line (hereinafter, described as a “character line”) is effective. Further, in order to suppress the influence of an edge effect in an electrophotographic printer, it is also known that density unevenness correction processing to adjust a gradation value in the vicinity of a solid edge portion is effective.
The image processing apparatus disclosed in Japanese Patent Laid-Open No. 2006-295624 identifies the edge type by using a pattern matching technique. In more detail, this image processing apparatus collates a local pixel block cut out from input image data with a plurality of pixel patterns stored in advance and identifies the edge type based on the collation results.